The present invention relates to an installation for depositing thin layers over a large surface in the reactive vapour phase by plasma. It is used in depositing semiconductors, insulants or metals on large substrates (several decimeters), particularly made from an insulating material (such as glass). The favoured fields of application for the invention are the production of electronic circuits, flat display screens or solar cells.
The basic technology used in the invention is known. It consists of the decomposition of a gas acting as a carrier for an element to be deposited, by the action of a plasma produced by a high frequency field. This method falls within the scope of the deposition process in the reactive gaseous phase, known as chemical vapour deposition or CVD. Compared with the CVD process in which the gas is decomposed by heating it, the use of a plasma has the advantage of leading to a relatively low operating temperature (below 600.degree. C.), which makes it possible to use inexpensive substrates such as glass.
The hitherto known plasma CVD installations do not make it possible to obtain large surface layers with a good homogeneity.